This invention relates to copolymers derived from p-dioxanone and its homologs, and especially to such crystalline copolymers which can be readily melt spun to prepare fibers suitable for use as absorbable surgical sutures.
U.S. Pat. No. 4,052,988 (Doddi) discloses the preparation of a p-dioxanone homopolymer and its use as an absorbable surgical suture. This synthetic suture exhibits outstanding mechanical and biological properties which make it a viable candidate to replace natural sutures such as surgical gut and collagen for numerous applications.
One of the significant hurdles to overcome before surgeons readily accept a synthetic suture over natural sutures is the stiffness of synthetics. As an example, a well known synthetic suture, which can be prepared from a glycolide homopolymer or a copolymer of lactide and glycolide, is typically braided or twisted to prepare a multifilament suture so that the suture has the requisite flexibilty and handling characteristics. One of the goals of the polymer chemist attempting to synthesize polymers suitable for use as absorbable surgical sutures is to prepare a monofilament suture which has handling properties and flexibility comparable to such properties of multifilament, braided sutures commonly used in the art without sacrificing physical properties.
Although the p-dioxanone homopolymer described in the Doddi Patent goes a long way in reaching the goal toward the preparation of an absorbable monofilament suture with handling properties and flexibilty as good as a braided multifilament, it would be desirable to develop a polymer composition which has even better flexibility relative to a p-dioxanone homopolymer without sacrificing physical properties.